Hours later, Qatar’s state-run television also announced that it had shut down its website temporarily “for security reasons” after hacking attempts, it said on its Twitter feed.

The network is the major broadcaster for Qatar, which is in a standoff with fellow Arab states over alleged ties to terrorism. The row is endangering stability in the region.

On Monday, Saudi Arabia, the UAE, Egypt and Bahrain launched an unprecedented campaign to isolate Qatar diplomatically and economically over links to the Muslim Brotherhood, Hamas and Iran, sparking the worst diplomatic crisis in the region for 30 years.

All four countries withdrew their ambassadors and launched an economic blockade, including denial of airspace, leading to panic-buying in the Qatari capital, Doha. They have isolated the country by land, sea and air. On Thursday , the UAE took a further step of refusing to send on mail to Qatar.

It is believed that the Russian government was not involved in the hacks; instead, freelance hackers were paid to carry out the work on behalf of some other state or individual. Some observers have claimed privately that Saudi Arabia or the UAE may have commissioned the hackers.

The Saudi foreign minister, Adel al-Jubeir, said he had no knowledge of the results of the FBI inquiry. The Russian government has denied any involvement in the hacking.

Qatar is a critical player in the Middle East as the largest exporter of liquid gas, the host to the largest US military base in the region and the venue for the 2022 World Cup.